linux-stable.git/kernel/torture.c, branch v4.18.2

rcu: Rename cond_resched_rcu_qs() to cond_resched_tasks_rcu_qs()

2018-05-15T17:27:29+00:00

Commit e31d28b6ab8f ("trace: Eliminate cond_resched_rcu_qs() in favor
of cond_resched()") substituted cond_resched() for the earlier call
to cond_resched_rcu_qs().  However, the new-age cond_resched() does
not do anything to help RCU-tasks grace periods because (1) RCU-tasks
is only enabled when CONFIG_PREEMPT=y and (2) cond_resched() is a
complete no-op when preemption is enabled.  This situation results
in hangs when running the trace benchmarks.

A number of potential fixes were discussed on LKML
(https://lkml.kernel.org/r/20180224151240.0d63a059@vmware.local.home),
including making cond_resched() not be a no-op; making cond_resched()
not be a no-op, but only when running tracing benchmarks; reverting
the aforementioned commit (which works because cond_resched_rcu_qs()
does provide an RCU-tasks quiescent state; and adding a call to the
scheduler/RCU rcu_note_voluntary_context_switch() function.  All were
deemed unsatisfactory, either due to added cond_resched() overhead or
due to magic functions inviting cargo culting.

This commit renames cond_resched_rcu_qs() to cond_resched_tasks_rcu_qs(),
which provides a clear hint as to what this function is doing and
why and where it should be used, and then replaces the call to
cond_resched() with cond_resched_tasks_rcu_qs() in the trace benchmark's
benchmark_event_kthread() function.

Reported-by: Steven Rostedt 
Signed-off-by: Paul E. McKenney 
Tested-by: Nicholas Piggin

torture: Save a line in stutter_wait(): while -> for

2017-12-11T17:18:30+00:00

Signed-off-by: Paul E. McKenney

torture: Eliminate torture_runnable and perf_runnable

2017-12-11T17:18:29+00:00

The purpose of torture_runnable is to allow rcutorture and locktorture
to be started and stopped via sysfs when they are built into the kernel
(as in not compiled as loadable modules).  However, the 0444 permissions
for both instances of torture_runnable prevent this use case from ever
being put into practice.  Given that there have been no complaints
about this deficiency, it is reasonable to conclude that no one actually
makes use of this sysfs capability.  The perf_runnable module parameter
for rcuperf is in the same situation.

This commit therefore removes both torture_runnable instances as well
as perf_runnable.

Reported-by: Thomas Gleixner 
Signed-off-by: Paul E. McKenney

torture: Make stutter less vulnerable to compilers and races

2017-12-11T17:18:29+00:00

The stutter_wait() function repeatedly fetched stutter_pause_test, and
should really just fetch it once on each pass.  The races should be
harmless, but why have the races?  Also, the whole point of the value
"2" for stutter_pause_test is to get everyone to start at very nearly
the same time, but the value "2" was the first jiffy of the stutter
rather than the last jiffy of the stutter.

This commit rearranges the code to be more sensible.

Signed-off-by: Paul E. McKenney

torture: Suppress CPU stall warnings during shutdown ftrace dump

2017-11-28T23:54:26+00:00

The torture_shutdown() function directly invokes ftrace_dump(), which
can result in RCU CPU stall warnings when the ftrace buffer is large,
which it usually is.  This commit therefore invoks rcu_ftrace_dump()
in place of ftrace_dump(), suppressing RCU CPU stall warnings during
this time.

Signed-off-by: Paul E. McKenney

torture: Fix typo suppressing CPU-hotplug statistics

2017-07-25T20:04:45+00:00

The torture status line contains a series of values preceded by "onoff:".
The last value in that line, the one preceding the "HZ=" string, is
always zero.  The reason that it is always zero is that torture_offline()
was incrementing the sum_offl pointer instead of the value that this
pointer referenced.  This commit therefore makes this increment operate
on the statistic rather than the pointer to the statistic.

Signed-off-by: Paul E. McKenney

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:27+00:00

We are going to split  out of , which
will have to be picked up from other headers and .c files.

Create a trivial placeholder  file that just
maps to  to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

scripts/spelling.txt: add "varible" pattern and fix typo instances

2017-02-28T02:43:47+00:00

Fix typos and add the following to the scripts/spelling.txt:

  varible||variable

While we are here, tidy up the comment blocks that fit in a single line
for drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c and
net/sctp/transport.c.

Link: http://lkml.kernel.org/r/1481573103-11329-11-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

torture: Convert torture_shutdown() to hrtimer

2016-08-22T17:01:49+00:00

Upcoming changes to the timer wheel introduce significant inaccuracy
and possibly also an ultimate limit on timeout duration.  This is a
problem for the current implementation of torture_shutdown() because
(1) shutdown times are user-specified, and can therefore be quite long,
and (2) the torture scripting will kill a test instance that runs for
more than a few minutes longer than scheduled.  This commit therefore
converts the torture_shutdown() timed waits to an hrtimer, thus avoiding
too-short torture test runs as well as death by scripting.

Signed-off-by: Paul E. McKenney 
Acked-by: Arnd Bergmann

torture: Stop onoff task if there is only one cpu

2016-06-14T23:03:28+00:00

If the whole system has only one cpu, that cpu won't be able to be
offlined, so there is no need onoff task is stil running.

Signed-off-by: Boqun Feng 
Signed-off-by: Paul E. McKenney